Circuit, base station, method, and recording medium

ABSTRACT

Circuitry for an aerial vehicle that includes processing circuitry that acquires altitude information indicating a measurement result of altitude of the aerial vehicle, receives a reference signal transmitted from a base station, receives altitude zone setting information transmitted from the base station, the altitude zone setting information being information for setting an altitude zone for classifying a state of the altitude zone of the aerial vehicle, identifies the altitude zone of the aerial vehicle based on the altitude information and the altitude zone setting information, and controls measurement report processing of reporting a measurement report message including reference signal information indicating a measurement result of the reference signal and the altitude information to the base station based on the altitude zone of the aerial vehicle, such that a frequency of transmitting the measurement report message is changed according to the identified altitude zone.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.16/324,573, filed Feb. 11, 2019, which is based on PCT filingPCT/JP2017/029407, filed Aug. 15, 2017, which claims priority to JP2016-188149, filed Sep. 27, 2016, the entire contents of each areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a circuit, a base station, a method,and a recording medium.

BACKGROUND ART

In recent years, research and development related to drones have beencarried out and are attracting interest. Drones are small unmannedaircraft also known as unmanned aerial vehicles (UAVs). According to theeconomic reports published by the US Association for Unmanned VehicleSystems International, the market size of drones was about 82 billiondollars in 2025 only in the US, and 1 hundred thousand new jobs areestimated to be created. Drones can provide products and informationusing air space which has not been used for any means on land, sea, orair. Therefore, drones are also called the industrial revolution of theair and are considered to be important business areas in the future.

In general, drones are assumed to fly while performing wirelesscommunication. Therefore, it is preferable to develop technologiesenabling drones to perform stable wireless communication. With regard towireless communication used by devices of which positions can bechanged, many technologies have been developed so far. For example, thefollowing Patent Literature 1 discloses a technology relating tohand-over by a mobile communication terminal on an aircraft whichcrosses coverages of respective base stations at high speed.

CITATION LIST Patent Literature

Patent Literature 1: US 2016/0029370A

DISCLOSURE OF INVENTION Technical Problem

However, wireless communication systems proposed in the foregoing patentliterature, or the like, are not designed on the assumption of devicessuch as drones which can fly freely in 3-dimensional space.

Accordingly, the present disclosure provides a structure of wirelesscommunication for a device which can fly freely in 3-dimensional space.

Solution to Problem

According to the present disclosure, there is provided a circuitincluding: an acquiring unit configured to acquire altitude informationindicating a measurement result of altitude; and a measurement reportcontrol unit configured to control measurement report processing ofreporting a measurement report message including reference signalinformation indicating a measurement result of a reference signaltransmitted from a base station and the altitude information to the basestation on the basis of relationship between the altitude informationacquired by the acquiring unit and altitude zone setting information.

In addition, according to the present disclosure, there is provided abase station including: a reference signal transmitting unit configuredto transmit a reference signal; and a notification unit configured tonotify a terminal device of altitude zone setting information, theterminal device controlling measurement report processing of reporting ameasurement report message including reference signal informationindicating a measurement result of the reference signal and altitudeinformation on the basis of relationship between the altitudeinformation indicating a measurement result of altitude and the altitudezone setting information.

In addition, according to the present disclosure, there is provided amethod including: acquiring altitude information indicating ameasurement result of altitude; and controlling, by a processor,measurement report processing of reporting a measurement report messageincluding reference signal information indicating a measurement resultof a reference signal transmitted from a base station and the altitudeinformation to the base station on the basis of relationship between theacquired altitude information and altitude zone setting information.

In addition, according to the present disclosure, there is provided amethod including: transmitting a reference signal; and notifying, by aprocessor, a terminal device of altitude zone setting information, theterminal device controlling measurement report processing of reporting ameasurement report message including reference signal informationindicating a measurement result of the reference signal and altitudeinformation on the basis of relationship between the altitudeinformation indicating a measurement result of altitude and the altitudezone setting information.

In addition, according to the present disclosure, there is provided arecording medium having a program recorded thereon, the program causinga computer to function as: an acquiring unit configured to acquirealtitude information indicating a measurement result of altitude; and ameasurement report control unit configured to control measurement reportprocessing of reporting a measurement report message including referencesignal information indicating a measurement result of a reference signaltransmitted from a base station and the altitude information to the basestation on the basis of relationship between the altitude informationacquired by the acquiring unit and altitude zone setting information.

In addition, according to the present disclosure, there is provided arecording medium having a program recorded thereon, the program causinga computer to function as: a reference signal transmitting unitconfigured to transmit a reference signal; and a notification unitconfigured to notify a terminal device of altitude zone settinginformation, the terminal device controlling measurement reportprocessing of reporting a measurement report message including referencesignal information indicating a measurement result of the referencesignal and altitude information on the basis of relationship between thealtitude information indicating a measurement result of altitude and thealtitude zone setting information.

Advantageous Effects of Invention

According to the present disclosure, as described above, it is possibleto provide a structure of wireless communication for a device which canfly freely in 3-dimensional space. Note that the effects described aboveare not necessarily limitative. With or in the place of the aboveeffects, there may be achieved any one of the effects described in thisspecification or other effects that may be grasped from thisspecification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram illustrating an example of aconfiguration of a system according to the present embodiment.

FIG. 2 is an explanatory diagram illustrating an example of legalrestrictions with respect to a drone.

FIG. 3 is an explanatory diagram illustrating an example of wirelesscommunication by a drone.

FIG. 4 is an explanatory diagram illustrating an example of wirelesscommunication by a drone.

FIG. 5 is an explanatory diagram illustrating an example of wirelesscommunication by a drone.

FIG. 6 is an explanatory diagram illustrating an example of wirelesscommunication by a drone.

FIG. 7 is a sequence diagram illustrating an example of flow ofhand-over procedure executed in the system according to the presentembodiment.

FIG. 8 is a block diagram illustrating an example of a logicalconfiguration of a base station according to the present embodiment.

FIG. 9 is a block diagram illustrating an example of a logicalconfiguration of a drone according to the present embodiment.

FIG. 10 is a flowchart illustrating an example of flow of measurementreport processing executed at the drone according to the presentembodiment.

FIG. 11 is a sequence diagram illustrating an example of flow ofmeasurement report processing performed in the system according to thepresent embodiment.

FIG. 12 is a block diagram illustrating a first example of a schematicconfiguration of an eNB.

FIG. 13 is a block diagram illustrating a second example of theschematic configuration of the eNB.

DISCLOSURE OF INVENTION

Hereinafter, a preferred embodiment of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Further, in the present specification and the drawings, differentletters are suffixed to the same reference numerals to distinguishelements which have substantially the same functional configuration. Forexample, a plurality of elements which has substantially the samefunctional configuration is distinguished such as base stations 100A,100B, and 100C, as necessary. Here, in a case in which it is notnecessary to particularly distinguish a plurality of elements which hassubstantially the same functional configuration, only the same referencenumeral is given. For example, in a case in which it is not necessary toparticularly distinguish base stations 100A, 100B, and 100C, the basestations 100A, 100B, and 100C are simply referred to as the basestations 100.

Note that description will be provided in the following order.

1. Introduction

1.1. Use cases of drone

1.2. Wireless communication by drone

1.3. General issues related to drone

1.4. System configuration example

1.5. Regulations

1.6. Hand-over

2. Configuration example of each device

2.1. Configuration example of base station

2.2. Configuration example of drone

3. Technical features

4. Application examples

5. Conclusion

1. INTRODUCTION 1.1. Use Cases of Drone

Various use cases of a drone are considered. Hereinafter, examples ofrepresentative use cases will be described.

Entertainment

For example, a use case in which a bird's-eye view photo, a movingimage, or the like, is captured by mounting a camera on a drone isconsidered. In recent years, it has become possible to easily performphotographing from viewpoint at which photographing was difficultbefore, such as dynamic photographing of sports events, or the like,from the ground.

Transportation

For example, a use case in which luggage is transported with a drone isconsidered. There is already a movement for starting serviceintroduction.

Public Safety

For example, a use case such as surveillance, criminal tracking, or thelike, is considered. Previously, there was also a movement for startingservice introduction.

Informative

For example, a use case in which information is provided using a droneis considered. Research and development of a drone base station which isa drone operating as a base station are already being carried out. Thedrone base station can provide a wireless service to an area in which itis difficult to build an Internet circuit by providing the wirelessservice from the sky.

Sensing

For example, a use case of measurement performed using a drone isconsidered. Since measurement previously performed by humans can nowalso be performed collectively by a drone, efficient measurement can beperformed.

Worker

For example, a use case in which a drone is used as a labor force isconsidered. For example, utilization of a drone for pesticide sprayingor pollination in a variety of areas of the agricultural industry isexpected.

Maintenance

For example, a use case in which maintenance is performed using a droneis considered. By using a drone, it is possible to perform maintenanceof a location such as the back of a bridge in which it is difficult forhumans to perform validation.

1.2. Wireless Communication by Drone

Utilization of a drone in the various cases has been examined above. Inorder to realize such use cases, various technical requests are imposedon the drone. Of the technical requests, communication can beexemplified particularly as an important request. Since a drone fliesfreely in 3-dimensional space, using wired communication is unrealisticand using wireless communication is assumed. Note that control (that is,remote manipulation) of a drone, supply of information from a drone, andthe like, are considered as purposes of the wireless communication.

Communication by a drone is also referred to as drone to X (D2X) in somecases. Communication partners of a drone in the D2X communication areconsidered to be, for example, another drone, a cellular base station, aWi-Fi (registered trademark) access point, a television (TV) tower, asatellite, a road side unit (RSU), and a human (or a device carried by ahuman), and the like. A drone can be remotely manipulated via device todevice (D2D) communication with a device carried by a human. Further, adrone can also be connected to a cellular system or Wi-Fi forcommunication. In order to further broaden coverage, a drone may be aconnected to a network in which a broadcast system such as TV is used ora network in which satellite communication is used, for communication.In this way, forming various communication links in a drone isconsidered.

1.3. General Issues Related to Drone

In general, in cellular communication, in order for a base stationdevice and a terminal device to efficiently perform wirelesscommunication, the base station device preferably controls radioresources efficiently. Therefore, in LTE, or the like, of the relatedart, the terminal device reports (that is, feeds back) measurementinformation of a transmission path with the base station device and/orterminal device state information to the base station device. Then, thebase station device controls the radio resources on the basis of theinformation reported from the terminal device.

However, a structure for the feedback control performed in the pastcellular communication has been designed on the premise that a terminaldevice is used on the ground or in a building, that is, a terminaldevice is used in 2-dimensional space. In other words, the structure forthe feedback control performed in the past cellular communication maynot be said to be appropriate for a drone which flies freely in3-dimensional space. Therefore, it is desirable that a structure forcellular communication is expanded for a drone.

1.4. System Configuration Example

Hereinafter, an example of a configuration of a system according to thepresent embodiment will be described with reference to FIG. 1.

FIG. 1 is an explanatory diagram illustrating an example of aconfiguration of a system according to the present embodiment. Asillustrated in FIG. 1, the system 1 according to the present embodimentincludes a base station 100, a terminal device 200 and a terminal device300.

A base station 100A is a macro cell base station which operates a macrocell 11A. The macro cell base station 100A is connected to a corenetwork 12. The core network 12 is connected to a packet data network(PDN) 13 via a gateway device (not illustrated). The macro cell 11A maybe operated in accordance with an arbitrary wireless communicationscheme such as, for example, long term evolution (LTE), LTE-advanced(LTE-A) and 5G. Note that, it is assumed that 5G includes new radio(NR), new radio access technology (NRAT), and further evolved universalterrestrial radio access (FEUTRA).

Base stations 100B and 100C are small cell base stations whichrespectively operate a small cell 11B and a small cell 11C. The smallcell base stations 100B and 100C are connected to the macro cell basestation 100A. The small cells 11B and 11C may be operated in accordancewith an arbitrary wireless communication scheme such as, for example,LTE, LTE-A and 5G.

The terminal devices 200 and 300 are devices which perform wirelesscommunication by being connected to cells operated by the base station100. As illustrated in FIG. 1, the terminal device 200 is a drone whichflies freely in 3-dimensional space. Further, the terminal device 300 isa device such as a smartphone which is assumed to move on a2-dimensional plane. In the following description, to distinguishbetween the terminal device 200 and the terminal device 300, theterminal device 200 will be also referred to as a drone 200. The drone200 can transmit and receive data in real time in a broad coverageprovided by, for example, cellular communication and receive control forautonomous flight by performing cellular communication. In an exampleillustrated in FIG. 1, a drone 200A and a terminal device 300A areconnected to the macro cell 11A provided by the macro cell base station100A, and a drone 200B and a terminal device 300B are connected to thesmall cell 11B provided by the small cell base station 100B.

Note that, in the following description, in the case where it is notparticularly necessary to distinguish between the macro cell basestation 100 and the small cell base station 100, these are collectivelyreferred to as the base station 100.

1.5. Regulations

It is assumed that regulations in accordance with altitude of flight areimposed on a drone.

The drone can stably and autonomously fly through advanced informationprocessing using information input from a plurality of sensors such as aglobal navigation satellite system (GNSS), a gyro sensor and an imagingelement. Therefore, the drone can realize highly automated flight orflight by efficient remote control for flight schedule from a place ofdeparture to a destination determined in advance. The drone can havevarious forms in accordance with various kinds of application. Forexample, in the case where the drone is a helicopter-type drone, thedrone has a variety of flight patterns.

The drone has a feature that it has an extremely high degree of freedomof existing with respect to altitude (for example, altitude above theground), unlike with a terminal device in related art such as asmartphone used by a person. Further, the drone has a feature that ithas extremely high moving speed in a vertical direction. For example, itis considered that, while the drone exists on the ground at a certaintime point, after flight is started, the drone reaches a height ofseveral tens of meters in the air after mere several seconds by steepclimbing. Further, it is also considered that flight of a drone terminalis switched to level flight after climbing, and the drone reaches apoint several hundreds of meters away after several tens of seconds,and, then, lowers its altitude to return to the height of the ground ata remote location.

There is a high possibility that certain legal restrictions may beimposed on a drone whose position varyingly changes with respect toaltitude at extremely high speed, for the purpose of securing safety inthe future. Currently, governmental institutions and private companiesare proposing legal restrictions. An example of possible legalrestrictions will be described with reference to FIG. 2.

FIG. 2 is an explanatory diagram illustrating an example of the legalrestrictions with respect to the drone. An X axis direction in FIG. 2means a horizontal direction, and a Z axis direction means a heightdirection. As illustrated in FIG. 2, it is considered that air space maybe divided into a plurality of regions of air space, and legalrestrictions may be imposed for each divided region of air space. Theair space can be divided in accordance with, for example, height and/ora type of building on the ground. Air space 21 is air space untilaltitude z₁, and, for example, flight at low speed is permitted. Airspace 22 is air space from altitude z₁ to altitude z₂, and, for example,flight at high speed is permitted. Air space 23 is air space fromaltitude z₂ to altitude z₃, which is air space over an area for whichrequirements for safety are high such as an area of high populationdensity and an airport, and, for example, flight itself is prohibited.Air space 24 is air space higher than altitude z₃, and, for example,flight by an authorized drone is permitted.

A user of the drone is required to manage flight of the drone stably andefficiently while complying with such legal restrictions. Further,cellular service providers are required to provide stable and efficientcommunication environments to drones also in the case where the numberof drones which perform cellular communication increases in the future.Further, the cellular service providers are required to preventdegradation of quality of service for terminal devices other thandrones.

1.6. Hand-Over

FIG. 3 is an explanatory diagram illustrating an example of wirelesscommunication by a drone 200. FIG. 3 is an example of a view of themacro cell 11A illustrated in FIG. 1 seen from a horizontal direction,an X axis direction means a horizontal direction, and a Z axis directionmeans a height direction. Because a drone 200A can move at high speedand in a wide area, the drone 200A can stably perform communication bybeing connected to the broad macro cell 11A provided by the macro cellbase station 100A. In this manner, for the drone 200, cellular in whicha communication distance is relatively long is more desirable than acommunication scheme such as Wi-Fi in which a communication distance isrelatively short, and particularly, connection with a macro cell whichis excellent in coverage is desirable.

However, it is assumed that communication by the drone 200 isaccompanied by a substantial amount of data communication such ascontrol data for flight and image information captured by the drone 200.Therefore, it is not desirable for the drone 200 to be always connectedto the macro cell to perform communication. To improve frequencyutilization efficiency of a network, avoid congestion, or the like, ifpossible, it is desirable that communication is made transition tocommunication performed by being connected to a small cell. By anoperator appropriately utilizing a small cell, it is possible to providestable data communication at high speed at low altitude whilesuppressing consumption of relatively expensive resources of a macrocell. Switching between a macro cell and a small cell will be describedwith reference to FIG. 4.

FIG. 4 is an explanatory diagram illustrating an example of wirelesscommunication by the drone 200. FIG. 4 is an example of a view of themacro cell 11A and the small cell 11B illustrated in FIG. 1 seen fromthe horizontal direction, an X axis direction means a horizontaldirection, and a Z axis direction means a height direction. Asillustrated in FIG. 4, in the case where the drone 200B is located (thatis, flies) near the ground, it is desirable that the drone 200B isconnected to the small cell 11B provided by the small cell base station100B. Meanwhile, in the case where the drone 200B is located at highaltitude, it is desirable that the drone 200B is connected to the macrocell 11A provided by the macro cell base station 100A. By a connectiondestination being switched in this manner, it is possible to realizeboth increase in capacity of the small cell to accommodate terminals andstability provided by connection in a broad area by a macro cell.

In this manner, in terms of efficient utilization of radio resources andflight stability of the drone 200, it is desirable that hand-over inassociation with climbing and descent of the drone 200 is executed.

Here, as described above, it is assumed that regulations regardingflight altitude may be imposed on the drone 200. Then, it is assumedthat the drone 200 is used by a flight plan in accordance with adetermined rule of flight altitude being programmed in advance on thebasis of the regulations. For example, it is assumed that the drone 200continues to climb after taking off from the ground, and starts levelflight at high speed when reaching a predetermined altitude zone (forexample, a high-speed flight altitude zone 31).

Concerning this point, in cellular communication in related art, atiming of hand-over based on received signal strength of a referencesignal transmitted from the base station is defined. In the case wherethe drone 200 performs hand-over on the basis of the received signalstrength in a similar manner, there can occur a gap between the timingof hand-over based on the received signal strength and a boundary offlight altitude defined by the regulations. This point will be describedin detail with reference to FIG. 5 and FIG. 6.

FIG. 5 is an explanatory diagram illustrating an example of wirelesscommunication by the drone 200. FIG. 5 is an example of a view of themacro cell 11A and the small cell 11B illustrated in FIG. 1 seen from ahorizontal direction, an X axis direction means a horizontal direction,and a Z axis direction means a height direction. As illustrated in FIG.5, there can be a case where an upper limit of the small cell 11B whoseboundary is defined with power does not intersect with a lower limit ofthe high-speed flight altitude zone 31. In this case, the drone 200hands over to the macro cell 11A at an upper end (for example, aposition indicated with a reference numeral 32) of the small cell 11B.Then, if the drone 200 reaches the high-speed flight altitude zone 31,the drone 200 starts high-speed flight in a state where connection withthe macro cell 11A is maintained. In this case, connection of the drone200 transitions to connection with the macro cell 11A before the drone200 starts high-speed flight. That is, because the drone 200 startshigh-speed movement after securing a broad connection coverage inadvance, a problem does not particularly occur. Note that the high-speedflight altitude zone 31 can correspond to the air space 22 describedabove with reference to FIG. 2.

FIG. 6 is an explanatory diagram illustrating an example of wirelesscommunication by the drone 200. FIG. 6 is an example of a view of themacro cell 11A and the small cell 11B illustrated in FIG. 1 seen from ahorizontal direction, an X axis direction means a horizontal direction,and a Z axis direction means a height direction. As illustrated in FIG.6, there can be a case where an upper limit of the small cell 11B whoseboundary is defined with power intersects with the lower limit of thehigh-speed flight altitude zone 31. In this case, there is a possibilitythat the drone 200B may start high-speed flight in a state whereconnection with the small cell 11B is maintained. In this case, thedrone 200 tries to hand over to the macro cell 11A at an upper end (forexample, a position indicated with a reference numeral 32) of the smallcell 11B. Further, there can be also a case where the drone 200 crossesthe small cell in a short period of time. In such a case, there is apossibility that the drone 200 exceeds a cell range of the small cell ina short period of time.

It seems that a cell radius of the small cell is set sufficiently smallin accordance with the regulations on the drone 200. However, in such acase, strict restrictions are imposed on the cell radius of the smallcell, which is not appropriate. Further, it is not realistic torecognize and manage a size of the cell radius in the air.

As in the example illustrated in FIG. 6, if the drone 200 goes out fromthe cell range of the small cell in a short period of time, there is apossibility that hand-over may be failed due to influence of a time lagfrom measurement to execution of hand-over. To explain this point,first, hand-over procedure will be described with reference to FIG. 7.

FIG. 7 is a sequence diagram illustrating an example of flow of thehand-over procedure to be executed in the system 1 according to thepresent embodiment. The drone 200, the small cell base station 100B, themacro cell base station 100A and mobility management entity (MME) 12 areinvolved with the present sequence. Further, it is assumed that thedrone 200 is connected to the small cell base station 100B in advance.

As illustrated in FIG. 7, first, the small cell base station 100Btransmits a measurement configuration message to the drone 200 (stepS102). This measurement configuration message can be transmitted as, forexample, radio resource control (RRC) connection reconfigurationmessage. The drone 200 measures a reference signal transmitted from asurrounding base station on the basis of this measurement configurationmessage and system information (step S104). Then, the drone 200transmits a measurement report message including information indicatinga measurement result to the small cell base station 100B in the casewhere predetermined conditions are satisfied (step S106).

Then, the small cell base station 100B judges hand-over on the basis ofthe received measurement report message (step S108). In the case whereit is judged to perform hand-over, the small cell base station 100Btransmits a hand-over request message to a target base station (here,the macro cell base station 100A) (step S110). Then, the macro cell basestation 100A transmits an ACK signal in response to the receivedhand-over request message to the small cell base station 100B (stepS112). Then, the small cell base station 100B transmits an RRCconnection reconfiguration message for giving an instruction of movementof a cell to the drone 200 after receiving the ACK signal (step S114).

Then, the drone 200 performs procedure of detaching from a small cell towhich the drone 200 is being connected (step S116) and establishessynchronization with the macro cell base station 100A (step S118). Then,the macro cell base station 100A transmits a path switch request to theMME 12 (step S120) and receives an ACK signal (step S122). Then, thesmall cell base station 100B transfers packet data convergence protocol(PDCP) packet data unit (PDU) to the macro cell base station 100A.Further, the drone 200 transmits an RRC connection reconfigurationcompletion message to the macro cell base station 100A (step S126).

Referring to the flow described above, in the hand-over procedure, thereis a time lag from when the drone 200 performs measurement until whenhand-over is judged and the RRC connection reconfiguration message isreceived. Therefore, there is a possibility that the drone 200 which isbeing connected to the small cell exceeds the cell range of the smallcell in a short period of time by suddenly starting high-speed flight ata time point at which the drone 200 reaches certain altitude, andthereby fails to receive the RRC connection reconfiguration message. Asa result, the drone 200 does not execute hand-over, and, as a result,connection with the small cell base station 100 to which the drone 200has been connected is interrupted.

In this manner, there is a possibility that, due to a gap between thetiming of the hand-over based on the received signal strength and theboundary of the flight altitude defined by the regulations, the drone200 may fail in hand-over and lose connection.

Concerning circumstances described above, as one of related artsassuming communication between a mobile body which moves in a3-dimensional manner and a ground station, there is the above-describedPatent Literature 1. The above-described Patent Literature 1 discloses atechnique of causing a terminal on an aircraft to perform hand-over onthe basis of 3-dimensional position information of the aircraft.However, the above-described Patent Literature 1 nowhere studiesregulations regarding flight altitude which can be imposed. Therefore,the above-described Patent Literature 1 nowhere studies theabove-described gap between the timing of the hand-over based on thereceived signal strength and the boundary of flight altitude defined bythe regulations. While it is effective to perform measurement in advanceby a terminal to realize desirable hand-over, the above-described PatentLiterature 1 nowhere studies this point. Further, while it is effectiveto perform measurement in advance by a terminal to realize desirablehand-over, Patent Literature 1 does not study this point.

Therefore, in view of the above-described circumstances, the presentembodiment proposes a structure of wireless communication for the drone200 which flies freely in 3-dimensional space, more specifically, astructure of measurement report for realizing appropriate hand-over.

2. CONFIGURATION EXAMPLE OF EACH DEVICE 2.1. Configuration Example ofBase Station

FIG. 8 is a block diagram illustrating an example of a logicalconfiguration of the base station 100 according to the presentembodiment. As illustrated in FIG. 8, the base station 100 includes anantenna unit 110, a wireless communication unit 120, a networkcommunication unit 130, a storage unit 140 and a processing unit 150.

(1) Antenna Unit 110

The antenna unit 110 radiates a signal output from the wirelesscommunication unit 120 to space as a radio wave. Further, the antennaunit 110 converts a radio wave in space into a signal and outputs thesignal to the wireless communication unit 120.

(2) Wireless Communication Unit 120

The wireless communication unit 120 transmits and receives signals. Forexample, the wireless communication unit 120 transmits a downlink signalto the terminal device and receives an uplink signal from the terminaldevice.

(3) Network Communication Unit 130

The network communication unit 130 transmits and receives information.For example, the network communication unit 130 transmits information toother nodes, and receives information from other nodes. For example, theabove-described other nodes include other base stations and core networknodes.

(4) Storage Unit 140

The storage unit 140 temporarily or permanently stores programs andvarious kinds of data for operation of the base station 100.

(5) Processing Unit 150

The processing unit 150 provides various functions of the base station100. The base station 100 operates on the basis of control by theprocessing unit 150. The processing unit 150 includes a reference signaltransmitting unit 151, a notification unit 153 and a hand-over controlunit 155. Note that the processing unit 150 can further includeconstituent elements other than these constituent elements. That is, theprocessing unit 150 can perform operation other than operation of theseconstituent elements. Functions of the reference signal transmittingunit 151, the notification unit 153 and the hand-over control unit 155will be described in detail later.

2.2. Configuration Example of Drone

FIG. 9 is a block diagram illustrating an example of a logicalconfiguration of the drone 200 according to the present embodiment. Asillustrated in FIG. 9, the drone 200 according to the present embodimentincludes an antenna unit 210, a to wireless communication unit 220, astorage unit 230, a flight device 240 and a processing unit 250.

(1) Antenna Unit 210

The antenna unit 210 radiates a signal output from the wirelesscommunication unit 220 to space as a radio wave. Further, the antennaunit 210 converts a radio wave in space into a signal and outputs thesignal to the wireless communication unit 220.

(2) Wireless Communication Unit 220

The wireless communication unit 220 transmits and receives signals. Forexample, the wireless communication unit 220 receives a downlink signalfrom the base station and transmits an uplink signal to the basestation.

(3) Storage Unit 230

The storage unit 230 temporarily or permanently stores programs andvarious kinds of data for operation of the terminal device 200.

(4) Flight Device 240

The flight device 240 is a device that has a flight ability, that is,can fly. The flight device 240 includes a driving unit 241, a batteryunit 242, a sensor unit 243, and a flight control unit 244.

The driving unit 241 performs driving for causing the drone 200 to fly.The driving unit 241 includes, for example, a motor, propeller, atransfer mechanism that transfers power of the motor to the propeller,and the like. The battery unit 242 supplies power to each constituentelement of the flight device 240. The sensor unit 243 senses variouskinds of information. For example, the sensor unit 243 includes a gyrosensor, an acceleration sensor, a positional information acquisitionunit (for example, a signal positioning unit of the global navigationsatellite system (GNSS)), an altitude sensor, a remaining batterysensor, a rotational sensor of the motor, and the like. The flightcontrol unit 244 performs control for causing the drone 200 to fly. Forexample, the flight control unit 244 controls the driving unit 241 onthe basis of sensor information obtained from the sensor unit 243 suchthat the drone 200 is caused to fly.

(5) Processing Unit 250

The processing unit 250 provides various functions of the terminaldevice 200. The processing unit 250 includes an acquiring unit 251 and ameasurement report control unit 253. Note that the processing unit 250can further include constituent elements other than these constituentelements. That is, the processing unit 250 can perform operation otherthan operation of these constituent elements. Functions of the acquiringunit 251 and the measurement report control unit 253 will be describedin detail later.

The processing unit 250 is connected to the flight device 240. Theprocessing unit 250 may be realized as a processor, a circuit, anintegrated circuit, or the like.

3. TECHNICAL FEATURES

(1) Measurement of Reference Signal

The base station 100 (for example, the reference signal transmittingunit 151) transmits a reference signal. The drone 200 (for example, themeasurement report control unit 253) then measures the reference signaltransmitted from the base station 100 to obtain reference signalinformation indicating the measurement result. The reference signalinformation includes information indicating signal quality such asreference signal received power (RSRP) and reference signal receivedquality (RSRQ) of, for example, a primary cell or an adjacent cell. Suchmeasurement processing is performed also in related art to performhand-over in LTE.

(2) Altitude Information

The drone 200 (for example, the acquiring unit 251) acquires altitudeinformation indicating a measurement result of altitude. For example,the altitude information can be measured by the sensor unit 243. Thatis, the drone 200 can acquire the altitude information from the flightdevice 240. There can be various methods for measuring the altitudeinformation. For example, the altitude information may be measured bythe drone 200 radiating an electromagnetic wave such as a radio wave,infrared light and laser light to the ground. Further, the altitudeinformation may be obtained by the GNSS. Further, the altitudeinformation may be estimated from a measurement result of an atmosphericpressure on the basis of relationship between an atmospheric pressureand altitude. Further, the altitude information may be obtained by radiowaves transmitted from a plurality of base stations 100 being received.

The drone 200 may further improve accuracy of the altitude informationby combining two or more of these measurement methods. Further, thedrone 200 may further improve accuracy of the altitude information bycorrecting the measured altitude information using correction datatransmitted from the base station 100.

In addition, the altitude information may be measured by other devices.For example, the altitude information may be measured by another drone200 which flies near the drone 200. Further, the altitude informationmay be obtained by the plurality of base stations 100 receiving radiowaves transmitted from the drone 200. In these cases, the drone 200receives the altitude information from other devices.

(3) Altitude Zone Setting Information

The base station 100 (for example, the notification unit 153) notifiesthe drone 200 of altitude zone setting information.

The altitude zone setting information is information for setting analtitude zone for classifying a state of the altitude of the drone 200.The drone 200 can determine an altitude zone to which the drone 200belongs on the basis of relationship between the acquired altitudeinformation and the altitude zone setting information. Note that,because the set altitude zone corresponds to the above-describedregulations, the altitude zone setting information can differ dependingon countries or areas.

The altitude zone setting information includes at least settingregarding an altitude zone in which high-speed flight is possible (forexample, the air space 22 illustrated in FIG. 2, the high-speed flightaltitude zone 31 illustrated in FIG. 5 or FIG. 6). In addition, thealtitude zone setting information can include setting regarding variouskinds of altitude zones such as an altitude zone in which low-speedflight is possible (for example, the air space 21 illustrated in FIG.2).

The altitude zone setting information includes thresholds for specifyingthe altitude zone, such as, for example, upper limit altitude H₁ andlower limit altitude H₂ of the altitude zone. Then, the drone 200determines relationship between the altitude information and thealtitude zone setting information on the basis of these thresholds. Forexample, the drone 200 determines that the altitude falls within thehigh-speed flight altitude zone if the altitude of the drone 200indicated by the altitude information is equal to or higher than H₁ andequal to or lower than H₂ and, otherwise, determines that the altitudedoes not fall within the high-speed flight altitude zone on the basis ofthe altitude zone setting information regarding the high-speed flightaltitude zone.

The altitude zone setting information may further include a value H_(M)for providing a margin (that is, offset) to the thresholds forspecifying the altitude zone. In the case where the altitude zonesetting information includes the margin H_(M), the drone 200 determinesthe altitude zone to which the drone 200 belongs while also taking intoaccount the margin H_(M) along with the upper limit altitude H₁ and thelower limit altitude H₂.

The drone 200 may determine relationship between the altitudeinformation and the altitude zone setting information while a hysteresisis provided. That is, the drone 200 may provide a hysteresis totransition of the altitude zone to which the drone 200 belongs.Specifically, the drone 200 determines that the drone 200 belongs to thealtitude zone after movement in the case where the drone 200 moves to adifferent altitude zone and flies in the altitude zone after movementfor equal to or longer than a predetermined time period. In other words,even if the drone 200 moves to a different altitude zone, the drone 200determines that the drone 200 belongs to the original altitude zoneuntil the drone 200 flies in the altitude zone after movement for equalto or longer than the predetermined time period. By this means, it ispossible to suppress excessively frequent transition of the altitudezone which can occur by the drone 200 flies near the boundary of thealtitude zones. The altitude zone setting information may include atimer value which provides the above-described predetermined time periodfor this hysteresis. The drone 200 determines that there is change inthe altitude zone in the case where the changed altitude zone ismaintained for a period exceeding the timer value included in thealtitude zone setting information.

There can be various notification methods of the altitude zone settinginformation. For example, the base station 100 may make a notificationof the altitude zone setting information included in system information(for example, a master information block (MIB) or a system informationblock (SIB)). Further, the base station 100 may make a notification ofthe altitude zone setting information included in information which isindividually provided for each drone 200, such as a measurementconfiguration information element (IE) provided in the RRC connectionreconfiguration message.

Further, the altitude zone setting information may include informationindicating a value to be set or may include information indicating achanged value from current setting.

Note that the altitude zone setting information may be set at the drone200 in advance.

(4) Measurement Report

The drone 200 (for example, the measurement report control unit 253)controls measurement report processing on the basis of relationshipbetween the acquired altitude information and altitude zone settinginformation.

Specifically, the drone 200 uses a parameter in accordance with therelationship between the altitude information and the altitude zonesetting information in the measurement report processing. By this means,the drone 200 can recognize or predict in advance transition of thealtitude zone and reflect the transition on the measurement reportprocessing, so that the drone 200 can perform appropriate hand-over inassociation with the reflection.

For example, in the case where the altitude zone set by the altitudezone setting information includes altitude indicated by the altitudeinformation, the drone 200 controls the measurement report processingusing the parameter in accordance with the altitude zone. That is, thedrone 200 controls the measurement report processing using the parameterin accordance with the altitude zone to which the drone 200 belongs. Inaddition, in the case where a difference between an upper limit or alower limit of the altitude zone set by the altitude zone settinginformation and the altitude information is within a threshold, thedrone 200 may control the measurement report processing using theparameter in accordance with the altitude zone. For example, the drone200 may control the measurement report processing using a parameter inaccordance with an adjacent altitude zone to which the drone 200 comesclose within an offset (that is the margin H_(M)) even if the drone 200does not actually belong to the adjacent altitude zone. By this means,the drone 200 can use the parameter of the altitude zone to which it ispredicted that the drone 200 belongs in near feature, ahead. Further,the drone 200 may control the measurement report processing using aparameter in accordance with that the drone 200 is located at theboundary of the altitude zones in the case where the drone 200 comesclose to the adjacent altitude zone within an offset (that is, themargin H_(M)). By this means, in the case where the drone 200 flies nearthe boundary of the altitude zones, the drone 200 can, for example,exceptionally increase measurement frequency and reporting frequency.

Here, the measurement report processing to be controlled can includemeasurement of a reference signal transmitted from the base station 100and reporting of a measurement report message including the referencesignal information indicating a measurement result to the base station100. This reporting is performed also in related art to performhand-over. Further, the measurement report processing to be controlledcan include measurement of altitude and reporting of a measurementreport message including the altitude information indicating ameasurement result to the base station 100. The measurement reportmessage to be transmitted to the base station 100 may include thereference signal information and the altitude information or may includeone of the reference signal information and the altitude information.

There are two types of control of the measurement report processing inaccordance with the relationship between the altitude information andthe altitude zone setting information, that is, control of a measurementtiming and control of a report timing. These will be respectivelydescribed below.

Measurement Timing

The drone 200 (for example, the measurement report control unit 253) maycause the altitude to be measured at a timing based on a parameter inaccordance with the relationship between the altitude information andthe altitude zone setting information. For example, the drone 200 causesthe altitude to be measured at a timing based on a parameter (such as,for example, an h-scale which will be described later) in accordancewith the altitude zone to which the drone 200 belongs, the adjacentaltitude zone to which the drone 200 comes close within an offset or theboundary of the altitude zones. By this means, the drone 200 can, forexample, increase measurement frequency as the altitude is higher orincrease measurement frequency of the altitude near the boundary of thehigh-speed flight altitude zone, or the like, to contribute to judgementof hand-over by the base station 100. Note that the measurement accuracycan increase as the measurement frequency increases.

The base station 100 notifies the drone 200 of altitude measurementtiming setting information including the parameter regarding themeasurement timing of the altitude. Then, the drone 200 measures thealtitude at a timing based on the altitude measurement timing settinginformation. The altitude setting timing setting information may beincluded in, for example, the measurement configuration IE provided inthe RRC connection reconfiguration message and notified.

For example, the altitude measurement timing setting informationincludes a parameter regarding a measurement pattern, such as ameasurement period and an offset value of the measurement timing. Anexample of a specific parameter and setting of the measurement timingbased on the parameter will be described below. For example, it isassumed that a scaling parameter of the measurement period is anh-scale, the parameter of the measurement period is an h-period and tomeasurement offset parameter is an h-offset. In this case, the drone 200measures the altitude at a timing of a subframe of a system frame number(SFN) calculated with the following equations.[Math. 1]SFN mod T=FLOOR(h−offset)  (1)[Math. 2]subframe=h−offset mod 10  (2)[Math. 3]T=FLOOR(h−period/h−scale)  (3)

According to the above-described equations, the measurement timing ofthe altitude comes with a period obtained by scaling the h-period withthe h-scale, and becomes a timing of the SFN at which a residue obtainedby dividing a value of the SFN with the period becomes equal to theh-offset. More specifically, the measurement timing of the altitudebecomes a timing of a subframe determined with reference to a value ofthe last digit of the h-offset in the above-described frame period ofthe SFN.

Note that the altitude measurement timing setting information mayinclude a parameter to be set itself or may include an amount of changefrom current setting.

Further, the reference signal may be measured at a timing in accordancewith the measurement timing of the altitude.

Report Timing

The drone 200 (for example, the measurement report control unit 253) mayreport the measurement report message to the base station 100 at atiming based on the parameter in accordance with the relationshipbetween the altitude information and the altitude zone settinginformation. For example, the drone 200 reports the measurement reportmessage at a timing based on the parameter (such as, for example, ans-measure which will be described later) in accordance with the altitudezone to which the drone 200 belongs, the adjacent altitude zone to whichthe drone 200 comes close within an offset or the boundary of thealtitude zones. By this means, the drone 200 can increase reportingfrequency, for example, near the boundary of the high-speed flightaltitude zone, or the like, to contribute to judgement of hand-over bythe base station 100.

The base station 100 notifies the drone 200 of the report timing settinginformation including the parameter regarding the report timing of thealtitude information. The drone 200 then reports the altitudeinformation at a timing based on the report timing setting information.The report timing setting information may be included in, for example,the measurement configuration IE provided in the RRC connectionreconfiguration message and notified.

Note that the report timing in LTE in related art is a timing at whichevents A1 to A6, or the like, occur, and parameters regarding the eventsA1 to A6 are provided from the base station as the measurementconfiguration IE (for example, ReportConfig). In the present embodiment,in addition to these parameters, the parameter regarding the altitudeinformation is included in the measurement configuration IE andnotified. Further, a new event regarding the altitude information may bedefined.

An example of information included in the report timing settinginformation will be described below.

For example, the report timing setting information may includeinformation indicating report conditions regarding measurement report ofthe reference signal. Specifically, the report timing settinginformation may include the s-measure. The s-measure is one ofparameters defining a timing of measurement report in LTE, and is athreshold corresponding to quality (for example, RSRP) of the referencesignal of a primary cell (PCell). In the case where the s-measure isincluded in the report timing setting information, the drone 200 updatesthe s-measure set at the drone 200. By this means, the drone 200 changesa transmission timing of the measurement report message.

Note that the report timing setting information may include an s-measuresuitable for the drone 200 separately from an s-measure suitable for theterminal device 300. Alternatively, the report timing settinginformation may include an offset value indicating a difference betweenan s-measure suitable for the terminal device 300 and an s-measuresuitable for the drone 200.

Further, the report timing setting information may include a scalingfactor for scaling the s-measure.

For example, the report timing setting information may includeinformation indicating reporting conditions regarding the altitudeinformation. Specifically, the report timing setting information mayinclude a threshold corresponding to the altitude information. In thecase where the report timing setting information includes a thresholdcorresponding to the altitude information, the drone 200 transmits themeasurement report message at a timing at which the altitude indicatedby the altitude information exceeds or falls below the threshold. Inthis manner, the drone 200 can transmit the measurement report messagein accordance with the altitude information.

For example, the report timing setting information may includeinformation indicating waiting time (for example, time-to-trigger (TTT))from when the reporting conditions are satisfied until when themeasurement report message is transmitted. In the case where the reporttiming setting information includes information indicating the waitingtime, the drone 200 transmits the measurement report message after thewaiting time has elapsed since the reporting conditions have beensatisfied. Note that the report timing setting information may include ascaling factor for scaling the waiting time.

Note that the report timing setting information may include a parameterto be set itself or may include an amount of change from currentsetting.

(5) Referring of Speed

The drone 200 (for example, the measurement report control unit 253) maycontrol the measurement report processing further on the basis of speedinformation indicating speed of the drone 200. The speed information tobe referred to for controlling the measurement report processing may beinformation indicating speed in a vertical direction such as climbingspeed and descent speed. In this case, the drone 200 can recognize withhigher accuracy or predict in advance transition of the altitude zoneand reflect the transition in the measurement report processing, so thatthe drone 200 can perform appropriate hand-over in association with thereflection. In addition, the speed information to be referred to forcontrolling the measurement report processing may be informationindicating speed in a 3-dimensional direction as well as a verticaldirection. In this case, the drone 200 can recognize or predict inadvance positional relationship with the cell range in the 3-dimensionaldirection and reflect the positional relationship in the measurementreport processing, so that the drone 200 can perform appropriatehand-over in association with the reflection.

To achieve this, first, the drone 200 (for example, the acquiring unit251) acquires speed information indicating a measurement result of thespeed. For example, the speed information can be measured by the sensorunit 243. That is, the drone 200 can acquire the speed information fromthe flight device 240. There can be various methods for measuring thespeed information. For example, the speed information may be calculatedon the basis of acceleration measured by an acceleration sensor.Further, the speed information may be calculated on the basis oftemporal change of the altitude indicated by the altitude information.

The drone 200 may further improve accuracy of the speed information bycombining two or more of these measurement methods. Further, the drone200 may further improve accuracy of the speed information by correctingthe measured speed information using correction data transmitted fromthe base station 100.

In addition, the speed information may be measured by other devices. Forexample, the speed information may be measured by another drone 200which flies near the drone 200. Further, the speed information may becalculated by the base station 100 on the basis of temporal change ofthe altitude indicated by the altitude information. In these cases, thedrone 200 receives the speed information from other devices.

Control of the measurement report processing in accordance with thespeed information includes control of the measurement timing and controlof the report timing in a similar manner to the control based on thealtitude information.

Measurement Timing

The drone 200 (for example, the measurement report control unit 253) maycause the altitude to be measured at a timing based on a parameter inaccordance with the speed information. By this means, the drone 200 can,for example, increase measurement frequency of the altitude as the speedis faster to contribute to judgement of hand-over by the base station100.

In this case, the altitude measurement timing setting informationnotified from the base station 100 to the drone 200 includes a parameterregarding the speed information. By this means, the measurement timingof the altitude becomes a timing based on the parameter regarding thespeed information. For example, the drone 200 measures the altitude at atiming at which the speed indicated by the speed information exceeds orfalls below a threshold. Further, the drone 200 may control ameasurement period in accordance with the speed information or may scalethe measurement period.

Report Timing

The drone 200 (for example, the measurement report control unit 253) mayreport the measurement report message to the base station 100 at atiming based on the parameter in accordance with the speed information.By this means, the drone 200 can, for example, increase reportingfrequency as the speed is faster to contribute to judgment of hand-overby the base station 100.

In this case, the report timing setting information notified from thebase station 100 to the drone 200 includes a parameter regarding thespeed information. By this means, the report timing becomes a timingbased on the parameter regarding the speed information. For example, thedrone 200 transmits the measurement report message at a timing at whichthe speed indicated by the speed information exceeds or falls below athreshold. Further, the drone 200 may control a report period inaccordance with the speed information or may scale the report period.

Of course, the measurement report processing may be controlled on thebasis of combination of the altitude information and the speedinformation. Further, the measurement report message may include thespeed information.

(6) Terminal Attribute Information

The drone 200 (for example, the measurement report control unit 253)notifies the base station 100 of information indicating that processingin accordance with the relationship between the altitude information andthe altitude zone setting information is performed. More simply, thedrone 200 notifies the base station 100 of information indicatingwhether or not the drone 200 has flight ability, that is, informationindicating whether or not the drone 200 is a drone. This informationwill be also referred to as terminal attribute information(corresponding to UE capability information in LTE) in the followingdescription.

The base station 100 can recognize that the drone 200 is a drone fromthe terminal attribute information and make a notification ofinformation for a drone (such as, for example, the altitude zone settinginformation, the altitude measurement timing setting information and thereport timing setting information). Note that the base station 100 maynotify the drone 200 of an inquiry message for requesting the drone 200to make a notification of the terminal attribute information.

(7) Measurement Report Message

The drone 200 reports the measurement report message to the base station100. This measurement report message includes at least one of thereference signal information or the altitude information. Typically, themeasurement report message includes both the reference signalinformation and the altitude information. Further, the measurementreport message may include the speed information.

The measurement report message includes a measurement result IEcorresponding to a measurement ID of a report target. Note that themeasurement ID is identification information associated with referencesignal measurement process or altitude measurement process.

There is a case where a period of the altitude measurement timing isdifferent from a period of the report timing. Therefore, for example,the measurement report message may include a plurality of pieces ofaltitude information or an average value of the plurality of pieces ofaltitude information. Further, the number of pieces of the altitudeinformation to be reported may be limited to a predetermined numberimmediately before reporting, or a predetermined number of pieces ofaltitude information or an average value of a predetermined number ofpieces of altitude information may be reported.

(8) Hand-Over

The base station 100 (for example, the hand-over control unit 155)controls hand-over processing in accordance with the measurement reportmessage reported from the drone 200. For example, the base station 100judges whether or not hand-over can be executed on the basis of at leastone of the altitude information, the speed information or the referencesignal information included in the measurement report message reportedfrom the drone 200 and selects a target base station. The base station100 transmits a hand-over request to the target base station in the casewhere hand-over is executed.

(9) Processing Flow

Processing flow in the present embodiment will be subsequently describedwith reference to FIG. 10 and FIG. 11.

FIG. 10 is a flowchart illustrating an example of flow of themeasurement report processing executed at the drone 200 according to thepresent embodiment. As illustrated in FIG. 10, first, the drone 200receives the altitude zone setting information from the base station 100(step S202). Then, the drone 200 sets the altitude measurement timing onthe basis of the relationship between the altitude information and thealtitude zone setting information (step S204). Then, the drone 200 setsthe report timing on the basis of the relationship between the altitudeinformation and the altitude zone setting information (step S206).Thereafter, the drone 200 measures the altitude in accordance with theset altitude measurement timing and reports the measurement reportmessage in accordance with the set report timing.

FIG. 11 is a sequence diagram illustrating an example of flow of themeasurement report processing executed in the system 1 according to thepresent embodiment. The base station 100 and the drone 200 are involvedwith the present sequence.

As illustrated in FIG. 11, the drone 200 acquires system informationfrom the base station 100 when the drone 200 camps on (step S302). Thissystem information includes, for example, the altitude zone settinginformation.

Then, the base station 100 inquires the terminal attribute informationto the drone 200 (step S304), and the drone 200 transmits the terminalattribute information to the base station 100 (step S306). By thismeans, the base station 100 recognizes that the communication partner isa drone.

Then, the base station 100 transmits, for example, the RRC connectionreconfiguration message including the altitude measurement timingsetting information and the report timing setting information to thedrone 200 (step S308). More specifically, the base station 100 transmitsa parameter for setting the measurement timing of the altitude and thereport timing in accordance with the relationship between the altitudeinformation and the altitude zone setting information to the drone 200.

Then, the drone 200 measures the altitude at a timing in accordance withthe altitude measurement timing setting information, that is, at atiming based on the parameter in accordance with the relationshipbetween the altitude information and the altitude zone settinginformation (step S310).

Then, the drone 200 performs reporting at a timing in accordance withthe report timing setting information. For example, the drone 200determines reporting conditions (step S312). More specifically, thedrone 200 determines whether or not the timing to be determined (forexample, current time) is a timing based on the parameter in accordancewith the relationship between the altitude information and the altitudezone setting information. Then, in the case where it is determined thatthe reporting conditions are satisfied, the drone 200 reports themeasurement report message including the reference signal informationand the altitude information to the base station 100 (step S314).

4. APPLICATION EXAMPLES

The technology according to the present disclosure can be applied tovarious products. For example, the base station 100 may be realized asany type of evolved Node B (eNB) such as a macro eNB or a small eNB. Thesmall eNB may be an eNB that covers a cell, such as a pico eNB, a microeNB, or a home (femto) eNB, smaller than a macro cell. Instead, the basestation 100 may be realized as another type of base station such as aNodeB or a base transceiver station (BTS). The base station 100 mayinclude a main entity (also referred to as a base station device) thatcontrols wireless communication and one or more remote radio heads(RRHs) disposed at different locations from the main entity. Further,various types of terminals to be described below may operate as the basestation 100 by performing a base station function temporarily orsemi-permanently.

4.1. Application Examples for Base Station First Application Example

FIG. 12 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. An eNB 800 includes one or more antennas 810and a base station device 820. Each antenna 810 and the base stationdevice 820 may be connected to each other via an RF cable.

Each of the antennas 810 includes a single or a plurality of antennaelements (e.g., a plurality of antenna elements constituting a MIMOantenna) and is used for the base station device 820 to transmit andreceive a wireless signal. The eNB 800 may include the plurality of theantennas 810 as illustrated in FIG. 12, and the plurality of antennas810 may, for example, correspond to a plurality of frequency bands usedby the eNB 800. It should be noted that while FIG. 12 illustrates anexample in which the eNB 800 includes the plurality of antennas 810, theeNB 800 may include the single antenna 810.

The base station device 820 includes a controller 821, a memory 822, anetwork interface 823, and a wireless communication interface 825.

The controller 821 may be, for example, a CPU or a DSP, and operatesvarious functions of an upper layer of the base station device 820. Forexample, the controller 821 generates a data packet from data in asignal processed by the wireless communication interface 825, andtransfers the generated packet via the network interface 823. Thecontroller 821 may generate a bundled packet by bundling data from aplurality of base band processors to transfer the generated bundledpacket. Further, the controller 821 may also have a logical function ofperforming control such as radio resource control, radio bearer control,mobility management, admission control, and scheduling. Further, thecontrol may be performed in cooperation with a surrounding eNB or a corenetwork node. The memory 822 includes a RAM and a ROM, and stores aprogram executed by the controller 821 and a variety of control data(such as, for example, terminal list, transmission power data, andscheduling data).

The network interface 823 is a communication interface for connectingthe base station device 820 to the core network 824. The controller 821may communicate with a core network node or another eNB via the networkinterface 823. In this case, the eNB 800 may be connected to a corenetwork node or another eNB through a logical interface (e.g., Siinterface or X2 interface). The network interface 823 may be a wiredcommunication interface or a wireless communication interface forwireless backhaul. In the case where the network interface 823 is awireless communication interface, the network interface 823 may use ahigher frequency band for wireless communication than a frequency bandused by the wireless communication interface 825.

The wireless communication interface 825 supports a cellularcommunication system such as long term evolution (LTE) or LTE-Advanced,and provides wireless connection to a terminal located within the cellof the eNB 800 via the antenna 810. The wireless communication interface825 may typically include a base band (BB) processor 826, an RF circuit827, and the like. The BB processor 826 may, for example, performencoding/decoding, modulation/demodulation, multiplexing/demultiplexing,and the like, and performs a variety of signal processing on each layer(e.g., L1, medium access control (MAC), radio link control (RLC), andpacket data convergence protocol (PDCP)). The BB processor 826 may havepart or all of the logical functions as described above instead of thecontroller 821. The BB processor 826 may be a module including a memoryhaving a communication control program stored therein, a processor toexecute the program, and a related circuit, and the function of the BBprocessor 826 may be changeable by updating the program. Further, themodule may be a card or blade to be inserted into a slot of the basestation device 820, or a chip mounted on the card or the blade.Meanwhile, the RF circuit 827 may include a mixer, a filter, anamplifier, and the like, and transmits and receives a wireless signalvia the antenna 810.

The wireless communication interface 825 may include a plurality of theBB processors 826 as illustrated in FIG. 12, and the plurality of BBprocessors 826 may, for example, correspond to a plurality of frequencybands used by the eNB 800. Further, the wireless communication interface825 may also include a plurality of the RF circuits 827, as illustratedin FIG. 12, and the plurality of RF circuits 827 may, for example,correspond to a plurality of antenna elements. Note that FIG. 12illustrates an example in which the wireless communication interface 825includes the plurality of BB processors 826 and the plurality of RFcircuits 827, but the wireless communication interface 825 may includethe single BB processor 826 or the single RF circuit 827.

In the eNB 800 illustrated in FIG. 12, one or more constituent elements(for example, the reference signal transmitting unit 151, thenotification unit 153, and/or the hand-over control unit 155) includedin the processing unit 150 described with reference to FIG. 8 may beimplemented in the wireless communication interface 825. Alternatively,at least some of the constituent elements may be implemented in thecontroller 821. As one example, a module including a part or the wholeof (for example, the BB processor 826) of the wireless communicationinterface 825 and/or the controller 821 may be implemented on the eNB800. The one or more constituent elements in the module may beimplemented in the module. In this case, the module may store a programcausing a processor to function as the one or more constituent elements(in other words, a program causing the processor to execute operationsof the one or more constituent elements) and execute the program. Asanother example, a program causing the processor to function as the oneor more constituent elements may be installed in the eNB 800, and thewireless communication interface 825 (for example, the BB processor 826)and/or the controller 821 may execute the program. In this way, the eNB800, the base station device 820, or the module may be provided as adevice including the one or more constituent elements and a programcausing the processor to function as the one or more constituentelements may be provided. In addition, a readable recording medium onwhich the program is recorded may be provided.

Further, in the eNB 800 illustrated in FIG. 12, the wirelesscommunication unit 120 described with reference to FIG. 8 may beimplemented in the wireless communication interface 825 (for example,the RF circuit 827). Further, the antenna unit 110 may be implemented atthe antenna 810. Further, the network communication unit 130 may beimplemented at the controller 821 and/or the network interface 823.Further, the storage unit 140 may be implemented at the memory 822.

Second Application Example

FIG. 13 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. An eNB 830 includes one or more antennas 840,a base station device 850, and an RRH 860. Each of the antennas 840 andthe RRH 860 may be connected to each other via an RF cable. Further, thebase station device 850 and the RRH 860 may be connected to each otherby a high speed line such as optical fiber cables.

Each of the antennas 840 includes a single or a plurality of antennaelements (e.g., antenna elements constituting a MIMO antenna), and isused for the RRH 860 to transmit and receive a wireless signal. The eNB830 may include a plurality of the antennas 840 as illustrated in FIG.13, and the plurality of antennas 840 may, for example, correspond to aplurality of frequency bands used by the eNB 830. Note that FIG. 13illustrates an example in which the eNB 830 includes the plurality ofantennas 840, but the eNB 830 may include the single antenna 840.

The base station device 850 includes a controller 851, a memory 852, anetwork interface 853, a wireless communication interface 855, and aconnection interface 857. The controller 851, the memory 852, and thenetwork interface 853 are similar to the controller 821, the memory 822,and the network interface 823 described with reference to FIG. 12.

The wireless communication interface 855 supports a cellularcommunication system such as LTE and LTE-Advanced, and provides wirelessconnection to a terminal located in a sector corresponding to the RRH860 via the RRH 860 and the antenna 840. The wireless communicationinterface 855 may typically include a BB processor 856 or the like. TheBB processor 856 is similar to the BB processor 826 described withreference to FIG. 12 except that the BB processor 856 is connected to anRF circuit 864 of the RRH 860 via the connection interface 857. Thewireless communication interface 855 may include a plurality of the BBprocessors 856, as illustrated in FIG. 13, and the plurality of BBprocessors 856 may, for example, correspond to a plurality of frequencybands used by the eNB 830. Note that FIG. 13 illustrates an example inwhich the wireless communication interface 855 includes the plurality ofBB processors 856, but the wireless communication interface 855 mayinclude the single BB processor 856.

The connection interface 857 is an interface for connecting the basestation device 850 (wireless communication interface 855) to the RRH860. The connection interface 857 may be a communication module forcommunication on the high speed line which connects the base stationdevice 850 (wireless communication interface 855) to the RRH 860.

Further, the RRH 860 includes a connection interface 861 and a wirelesscommunication interface 863.

The connection interface 861 is an interface for connecting the RRH 860(wireless communication interface 863) to the base station device 850.The connection interface 861 may be a communication module forcommunication on the high speed line.

The wireless communication interface 863 transmits and receives awireless signal via the antenna 840. The wireless communicationinterface 863 may typically include the RF circuit 864 or the like. TheRF circuit 864 may include a mixer, a filter, an amplifier and the like,and transmits and receives a wireless signal via the antenna 840. Thewireless communication interface 863 may include a plurality of the RFcircuits 864 as illustrated in FIG. 13, and the plurality of RF circuits864 may, for example, correspond to a plurality of antenna elements.Note that FIG. 13 illustrates an example in which the wirelesscommunication interface 863 includes the plurality of RF circuits 864,but the wireless communication interface 863 may include the single RFcircuit 864.

In the eNB 830 illustrated in FIG. 13, one or more constituent elements(for example, the reference signal transmitting unit 151, thenotification unit 153, and/or the hand-over control unit 155) includedin the processing unit 150 described with reference to FIG. 8 may beimplemented in the wireless communication interface 855 and/or thewireless communication interface 863. Alternatively, at least some ofthe constituent elements may be implemented in the controller 851. Asone example, a module including a part or the whole of (for example, theBB processor 856) of the wireless communication interface 825 and/or thecontroller 851 may be implemented on the eNB 830. The one or moreconstituent elements in the module may be implemented in the module. Inthis case, the module may store a program causing a processor tofunction as the one or more constituent elements (in other words, aprogram causing the processor to execute operations of the one or moreconstituent elements) and execute the program. As another example, aprogram causing the processor to function as the one or more constituentelements may be installed in the eNB 830, and the wireless communicationinterface 855 (for example, the BB processor 856) and/or the controller851 may execute the program. In this way, the eNB 830, the base stationdevice 850, or the module may be provided as a device including the oneor more constituent elements and a program causing the processor tofunction as the one or more constituent elements may be provided. Inaddition, a readable recording medium on which the program is recordedmay be provided.

Further, in the eNB 830 illustrated in FIG. 13, for example, thewireless communication unit 120 described with reference to FIG. 8 maybe implemented in the wireless communication interface 863 (for example,the RF circuit 864). Further, the antenna unit 110 may be implemented atthe antenna 840. Further, the network communication unit 130 may beimplemented at the controller 851 and/or the network interface 853.Further, the storage unit 140 may be implemented at the memory 852.

5. CONCLUSION

An embodiment of the present disclosure has been described in detailabove with reference to FIG. 1 to FIG. 13. As described above, the drone200 according to the present embodiment acquires the altitudeinformation indicating a measurement result of the altitude and controlsthe measurement report processing of reporting the measurement reportmessage including the reference signal information indicating ameasurement result of the reference signal transmitted from the basestation 100 and the altitude information to the base station 100 on thebasis of the relationship between the altitude information and thealtitude zone setting information. By this means, the base station 100can grasp the altitude of the drone 200 and cause the drone 200 toappropriately execute hand-over. In association with this, becausefailures of hand-over by the drone 200 are reduced, hand-over becomesefficient. As a result, an operator can realize accommodation of anumber of drones 200 using small cells.

The preferred embodiment of the present disclosure has been describedabove with reference to the accompanying drawings, whilst the presentdisclosure is not limited to the above examples. A person skilled in theart may find various alterations and modifications within the scope ofthe appended claims, and it should be understood that they willnaturally come under the technical scope of the present disclosure.

For example, while description has been provided that the drone 200 isnotified of the altitude zone setting information, the altitudemeasurement timing setting information and the report timing settinginformation from the base station 100, a source provider of theinformation is not limited to the base station 100. For example, theinformation may be provided from a server on the Internet, and the drone200 may be notified of the information by way of the base station 100.

Further, the drone 200 is not limited to a drone in a narrow sense. Forexample, the drone 200 may be an arbitrary flight vehicle controlled viacellular communication.

Further, while description has been provided above mainly concerning thehigh-speed flight altitude zone, the present technology is not limitedto such an example. For example, the present technology may be appliedto other altitude zones such as a low-speed flight altitude zone.

Further, the processing described using the flowcharts and the sequencediagrams in the present specification does not necessarily have to beexecuted in the illustrated order. Some processing steps may be executedin parallel. Further, additional processing steps may be employed, orpart of the processing steps may be skipped.

Further, the effects described in this specification are merelyillustrative or exemplified effects, and are not limitative. That is,with or in the place of the above effects, the technology according tothe present disclosure may achieve other effects that are clear to thoseskilled in the art from the description of this specification.

Additionally, the present technology may also be configured as below.

(1)

A circuit including:

an acquiring unit configured to acquire altitude information indicatinga measurement result of altitude; and

a measurement report control unit configured to control measurementreport processing of reporting a measurement report message includingreference signal information indicating a measurement result of areference signal transmitted from a base station and the altitudeinformation to the base station on the basis of relationship between thealtitude information acquired by the acquiring unit and altitude zonesetting information.

(2)

The circuit according to (1),

in which, in a case where an altitude zone set by the altitude zonesetting information includes altitude indicated by the altitudeinformation or in a case where a difference between an upper limit or alower limit of the altitude zone set by the altitude zone settinginformation and the altitude indicated by the altitude information iswithin a threshold, the measurement report control unit controls themeasurement report processing using a parameter in accordance with thealtitude zone.

(3)

The circuit according to (1) or (2),

in which the measurement report control unit causes altitude to bemeasured at a timing based on a parameter in accordance with therelationship.

(4)

The circuit according to any one of (1) to (3),

in which the measurement report control unit reports the measurementreport message to the base station at a timing based on a parameter inaccordance with the relationship.

(5)

The circuit according to any one of (1) to (4),

in which the acquiring unit acquires speed information, and

the measurement report control unit controls the measurement reportprocessing further on the basis of the speed information.

(6)

The circuit according to (5),

in which the measurement report control unit causes altitude to bemeasured at a timing based on a parameter in accordance with the speedinformation.

(7)

The circuit according to (5) or (6),

in which the measurement report control unit reports the measurementreport message to the base station at a timing based on a parameter inaccordance with the speed information.

(8)

The circuit according to any one of (5) to (7),

in which the speed information is information indicating speed in avertical direction.

(9)

The circuit according to any one of (1) to (8),

in which the measurement report control unit notifies the base stationof information indicating that processing in accordance with therelationship is performed.

(10)

The circuit according to any one of (1) to (9),

in which the measurement report control unit determines the relationshipwhile a hysteresis is provided.

(11)

The circuit according to any one of (1) to (10),

in which the altitude zone setting information includes at least settingregarding an altitude zone at which high-speed flight is possible.

(12)

The circuit according to any one of (1) to (11),

in which the acquiring unit acquires the altitude information from aflight device which is capable of flying.

(13)

The circuit according to (12),

in which the circuit is connected to the flight device.

(14)

A base station including:

a reference signal transmitting unit configured to transmit a referencesignal; and

a notification unit configured to notify a terminal device of altitudezone setting information, the terminal device controlling measurementreport processing of reporting a measurement report message includingreference signal information indicating a measurement result of thereference signal and altitude information on the basis of relationshipbetween the altitude information indicating a measurement result ofaltitude and the altitude zone setting information.

(15)

The base station according to (14),

in which the notification unit makes a notification of the altitude zonesetting information included in system information or a radio resourcecontrol (RRC) connection reconfiguration message.

(16)

The base station according to (14) or (15), further including:

a hand-over control unit configured to control hand-over processing inaccordance with the measurement report message reported from theterminal device.

(17)

A method including:

acquiring altitude information indicating a measurement result ofaltitude; and

controlling, by a processor, measurement report processing of reportinga measurement report message including reference signal informationindicating a measurement result of a reference signal transmitted from abase station and the altitude information to the base station on thebasis of relationship between the acquired altitude information andaltitude zone setting information.

(18)

A method including:

transmitting a reference signal; and

notifying, by a processor, a terminal device of altitude zone settinginformation, the terminal device controlling measurement reportprocessing of reporting a measurement report message including referencesignal information indicating a measurement result of the referencesignal and altitude information on the basis of relationship between thealtitude information indicating a measurement result of altitude and thealtitude zone setting information.

(19)

A recording medium having a program recorded thereon, the programcausing a computer to function as:

an acquiring unit configured to acquire altitude information indicatinga measurement result of altitude; and

a measurement report control unit configured to control measurementreport processing of reporting a measurement report message includingreference signal information indicating a measurement result of areference signal transmitted from a base station and the altitudeinformation to the base station on the basis of relationship between thealtitude information acquired by the acquiring unit and altitude zonesetting information.

(20)

A recording medium having a program recorded thereon, the programcausing a computer to function as:

a reference signal transmitting unit configured to transmit a referencesignal; and

a notification unit configured to notify a terminal device of altitudezone setting information, the terminal device controlling measurementreport processing of reporting a measurement report message includingreference signal information indicating a measurement result of thereference signal and altitude information on the basis of relationshipbetween the altitude information indicating a measurement result ofaltitude and the altitude zone setting information.

REFERENCE SIGNS LIST

-   1 system-   31 high-speed flight altitude zone-   100 base station-   110 antenna unit-   120 wireless communication unit-   130 network communication unit-   140 storage unit-   150 processing unit-   151 reference signal transmitting unit-   153 notification unit-   155 hand-over control unit-   200 terminal device, drone-   210 antenna unit-   220 wireless communication unit-   230 storage unit-   240 flight device-   241 driving unit-   242 battery unit-   243 sensor unit-   244 flight control unit-   250 processing unit-   251 acquiring unit-   253 measurement report control unit-   300 terminal device

The invention claimed is:
 1. A base station comprising: processingcircuitry configured to control transmission of a reference signal to aterminal device; control transmission of altitude zone settinginformation to the terminal device; and control reception of ameasurement report message from the terminal device, the measurementreport message including reference signal information indicating ameasurement result of the reference signal by the terminal device andaltitude information indicating a measurement result of altitude of anaerial vehicle, wherein the altitude zone setting information isinformation for setting an altitude zone for classifying a state of thealtitude zone of the aerial vehicle, the terminal device identifies thealtitude zone of the aerial vehicle based on the altitude informationand the altitude zone setting information, the terminal device controlsa measurement report processing of reporting the measurement reportmessage based on the identified altitude zone of the aerial vehicle,such that a frequency of transmitting the measurement report message ischanged according to the identified altitude zone of the aerial vehicle,and the processing circuitry is configured to control the reception ofthe measurement report message transmitted using the frequency.
 2. Thebase station according to claim 1, wherein the terminal device controlsthe measurement report processing of reporting the measurement reportmessage based on a relationship between the altitude information and thealtitude zone setting information.
 3. The base station according toclaim 1, wherein the altitude zone setting information is included insystem information or a radio resource control (RRC) connectionreconfiguration message.
 4. The base station according to claim 1,wherein the processing circuitry is further configured to controlhand-over processing in accordance with the measurement report messagereported from the terminal device.
 5. The base station according toclaim 1, wherein the terminal device changes the frequency oftransmitting the measurement report message such that the frequency ishigher as the identified altitude zone of the aerial vehicle becomeshigher.
 6. The base station according to claim 1, wherein the terminaldevice is provided in the aerial vehicle.
 7. The base station accordingto claim 1, wherein the altitude zone setting information includes atleast a setting regarding an altitude zone at which high-speed flighthigher than a predetermined threshold speed is possible.
 8. The basestation according to claim 1, wherein the aerial vehicle is an unmannedaerial vehicle.
 9. A method for a base station, the method comprising:controlling, using processing circuitry, transmission of a referencesignal; controlling, using the processing circuitry, transmission ofaltitude zone setting information to a terminal device; and controlling,using the processing circuitry, reception of a measurement reportmessage from the terminal device, the measurement report messageincluding reference signal information indicating a measurement resultof the reference signal by the terminal device and altitude informationindicating a measurement result of altitude of an aerial vehicle,wherein the altitude zone setting information is information for settingan altitude zone for classifying a state of the altitude zone of theaerial vehicle, the terminal device identifies the altitude zone of theaerial vehicle based on the altitude information and the altitude zonesetting information, and the terminal device controls a measurementreport processing of reporting the measurement report message based onthe identified altitude zone of the aerial vehicle, such that afrequency of transmitting the measurement report message is changedaccording to the identified altitude zone of the aerial vehicle.
 10. Themethod according to claim 9, wherein the terminal device controls themeasurement report processing of reporting the measurement reportmessage based on a relationship between the altitude information and thealtitude zone setting information.
 11. The method according to claim 9,wherein the altitude zone setting information is included in systeminformation or a radio resource control (RRC) connection reconfigurationmessage.
 12. The method according to claim 9, further comprising:controlling, using the processing circuitry, hand-over processing inaccordance with the measurement report message reported from theterminal device.
 13. The method according to claim 9, wherein theterminal device changes the frequency of transmitting the measurementreport message such that the frequency is higher as the identifiedaltitude zone of the aerial vehicle becomes higher.
 14. A non-transitorycomputer readable medium including executable instructions, which whenexecuted by a computer cause the computer to execute a method for a basestation, the method comprising: controlling transmission of a referencesignal; controlling transmission of altitude zone setting information toa terminal device; and controlling reception of a measurement reportmessage from the terminal device, the measurement report messageincluding reference signal information indicating a measurement resultof the reference signal by the terminal device and altitude informationindicating a measurement result of altitude of an aerial vehicle,wherein the altitude zone setting information is information for settingan altitude zone for classifying a state of the altitude zone of theaerial vehicle, the terminal device identifies the altitude zone of theaerial vehicle based on the altitude information and the altitude zonesetting information, and the terminal device controls a measurementreport processing of reporting the measurement report message based onthe identified altitude zone of the aerial vehicle, such that afrequency of transmitting the measurement report message is changedaccording to the identified altitude zone of the aerial vehicle.